A cabinet is known from EP-B-0 485 281, with a built-in swivel frame and mounting plates attached thereto, for carrying circuit boards that are vertically arranged on the rear side facing the inside of the cabinet, and which are separated from each other. If required to cool the heat produced by the circuit board components, there are air inlet ducts and fan inserts attached to the swivel frame under the mounting plates, each with two horizontally blowing axial fans. Deflectors are provided to guide the air streams vertically.
DE-A 27 10 356 also describes an aerated cabinet with a frame containing several cross bars, which allow the installation of two instrument housings next to each other in several superimposed rows. The instrument housings contain the groups of components to be cooled, and have slots in their bottom and top plates for the passage of cooling air. The latter is produced by two fan inserts placed in the frame rack between the lower row of instrument housings and the bottom of the cabinet. As viewed in the installation direction, each fan insert contains two vertically blowing axial fans placed next to each other.
Module carriers, for example in a 19" assembly system, are known from the publication DE-U-87 14 894; they can be equipped with different components and are mounted above each other in a frame, cabinet or housing. In an embodiment designed as a table housing, in addition to the side walls of the housing which is open on the front and has ventilation slots in the bottom and on the top, there are vertical profile rails to which the lateral flanges of the module carrier and the front plate of a fan insert are bolted, where the latter has an inserted filter mat instead of a bottom. Vertical profile rails attached horizontally to the guide rails facilitate the installation of the fan insert. Two vertically blowing axial fans are arranged next to each other behind the front plate of the fan insert, and the space behind them has connecting clamps for external lines that are connected to the axial fans' service lines.
When a defect has been signalled or the end of the service life of an axial fan, the replacement is complicated and time-consuming. In addition, this presupposes that the fan insert must be accessible from the rear of the housing for unclamping the external lines, before the attachment can be loosened from the vertical profile rails and the fan insert removed. Otherwise the external lines must have an excess length so that they can be pulled out of the housing together with the fan insert. This requires undesirable additional space for storing the excess lengths in the housing.